Battery type makes a difference with the Moonlight Headlamp
I get very reliable and satisfactory service with Duracell batteries in this unit. If I substitute batteries without insulation on the sides (usually one of the cheaper brands), I have sometimes have trouble with the light flickering on and off when the wire moves in certain directions. Whether this is the insulation, differences in battery dimensions, or variations in quality of electrical contacts is not immediately clear. However, moving the battery case wire may cause a very small movement in the two contacts in the case soldered to the wires.